
The seven crystal systems are a method of
classifying crystals according to their atomic lattice
or structure. The structures of all crystals can be
classified according to the symmetry of the unit cells.
There are in total 7 groups, collectively called Crystal
Systems: Triclinic, Monoclinic, Orthorhombic,
Tetragonal, Trigonal, Hexagonal, and Cubic. The
symmetry of each group is described by the
relationship between the lattice sides a, b, and c and
angles α, β and γ.